This week there was a discussion of the theories of the causes of autism. I will post here some websites that have interesting information on this particular topic. I will put some of the most pertinent information under the reference. http://mentalhealth.gov/health/publications/autism/complete-index.shtml#pub6
Research into Causes and Treatment of Autism Spectrum Disorders
Research into the causes, the diagnosis, and the treatment of autism spectrum disorders has advanced in tandem. With new well-researched standardized diagnostic tools, ASD can be diagnosed at an early age. And with early diagnosis, the treatments found to be beneficial in recent years can be used to help the child with ASD develop to his or her greatest potential.
Disorders/Vaccinations
The Institute of Medicine (IOM) conducted a thorough review on the issue of a link between thimerosal (a mercury based preservative that is no longer used in vaccinations) and autism. The final report from IOM, Immunization Safety Review: Vaccines and Autism, released in May 2004, stated that the committee did not find a link. Until 1999, vaccines given to infants to protect them against diphtheria, tetanus, pertussis, Haemophilus influenzae type b (Hib), and Hepatitis B contained thimerosal as a preservative. Today, with the exception of some flu vaccines, none of the vaccines used in the U.S. to protect preschool aged children against 12 infectious diseases contain thimerosal as a preservative. The MMR vaccine does not and never did contain thimerosal. Varicella (chickenpox), inactivated polio (IPV), and pneumococcal conjugate vaccines have also never contained thimerosal. A U.S. study looking at environmental factors including exposure to mercury, lead and other heavy metals is ongoing.
Research on the Biologic Basis of ASD
Because of its relative inaccessibility, scientists have only recently been able to study the brain systematically. But with the emergence of new brain imaging tools—computerized tomography (CT), positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI), study of the structure and the functioning of the brain can be done. With the aid of modern technology and the new availability of both normal and autism tissue samples to do postmortem studies, researchers will be able to learn much through comparative studies. Postmortem and MRI studies have shown that many major brain structures are implicated in autism. This includes the cerebellum, cerebral cortex, limbic system, corpus callosum, basal ganglia, and brain stem.29 Other research is focusing on the role of neurotransmitters such as serotonin, dopamine, and epinephrine . Research into the causes of autism spectrum disorders is being fueled by other recent developments. Evidence points to genetic factors playing a prominent role in the causes for ASD. Twin and family studies have suggested an underlying genetic vulnerability to ASD.30To further research in this field, the Autism Genetic Resource Exchange, a project initiated by the Cure Autism Now Foundation, and aided by an NIMH grant, is recruiting genetic samples from several hundred families. Each family with more than one member diagnosed with ASD is given a 2-hour, in-home screening. With a large number of DNA samples, it is hoped that the most important genes will be found. This will enable scientists to learn what the culprit genes do and how they can go wrong. Another exciting development is the Autism Tissue Program (http://www.brainbank.org), supported by the Autism Society of America Foundation, the Medical Investigation of Neurodevelopmental Disorders (M.I.N.D.) Institute at the University of California, Davis, and the National Alliance for Autism Research. The program is aided by a grant to the Harvard Brain and Tissue Resource Center (http://www.brainbank.mclean.org), funded by the National Institute of Mental Health (NIMH) and the National Institute of Neurological Disorders and Stroke (NINDS). Studies of the postmortem brain with imaging methods will help us learn why some brains are large, how the limbic system develops, and how the brain changes as it ages. Tissue samples can be stained and will show which neurotransmitters are being made in the cells and how they are transported and released to other cells. By focusing on specific brain regions and neurotransmitters, it will become easier to identify susceptibility genes. Recent neuroimaging studies have shown that a contributing cause for autism may be abnormal brain development beginning in the infant’s first months. This“growth dysregulation hypothesi” holds that the anatomical abnormalities seen in autism are caused by genetic defects in brain growth factors. It is possible that sudden, rapid head growth in an infant may be an early warning signal that will lead to early diagnosis and effective biological intervention or possible prevention of autism.31
We had some discussion about genetics versus environment. Here is a study that examines that.
Environmental factors may be more important than previously thought in determining whether a child develops autism, says a study of twins published online in July by theArchives of General Psychiatry. The findings shake up prior assumptions that genetics were largely the culprit behind the neurodevelopmental disorder, now estimated to affect 1% of the population. The study, believed to be the largest of its kind, looked at 192 pairs of identical and fraternal twins, in which at least one child in each pair had strict autism or a milder autism spectrum disorder (archpsyc.ama-assn.org/cgi/content/abstract/archgenpsychiatry.2011.76/).
June 8, 2011 -- Genetic mutations not inherited from parents appear to explain some cases of autism, new research suggests. And the mutations may number in the hundreds. While the new research is a step forward, it is a small puzzle piece. "It could explain up to 2% of all autism cases," says researcher Stephan J. Sanders, MD, a postdoctoral research associate at Yale University's Child Study Center. Even so, he says the new research -- reported as a trio of studies in the journalNeuron -- provides a solid foundation to a better understanding of the biology of the disorder, eventually leading to better treatments. In the new research, scientists also found new clues about why boys seem to be more vulnerable to the disorder than girls. ''In combination with some other research studies, this new research shows pretty clearly there is indeed a strong genetic component to autism, and that the individual genes can be identified," say Alan Packer, PhD, associate director for research at the Simons Foundation. It funds autism research and provided the sample populations studied in the new research.
http://mentalhealth.gov/health/publications/autism/complete-index.shtml#pub6
Research into Causes and Treatment of Autism Spectrum Disorders
Research into the causes, the diagnosis, and the treatment of autism spectrum disorders has advanced in tandem. With new well-researched standardized diagnostic tools, ASD can be diagnosed at an early age. And with early diagnosis, the treatments found to be beneficial in recent years can be used to help the child with ASD develop to his or her greatest potential.Disorders/Vaccinations
The Institute of Medicine (IOM) conducted a thorough review on the issue of a link between thimerosal (a mercury based preservative that is no longer used in vaccinations) and autism. The final report from IOM, Immunization Safety Review: Vaccines and Autism, released in May 2004, stated that the committee did not find a link.Until 1999, vaccines given to infants to protect them against diphtheria, tetanus, pertussis, Haemophilus influenzae type b (Hib), and Hepatitis B contained thimerosal as a preservative. Today, with the exception of some flu vaccines, none of the vaccines used in the U.S. to protect preschool aged children against 12 infectious diseases contain thimerosal as a preservative. The MMR vaccine does not and never did contain thimerosal. Varicella (chickenpox), inactivated polio (IPV), and pneumococcal conjugate vaccines have also never contained thimerosal.
A U.S. study looking at environmental factors including exposure to mercury, lead and other heavy metals is ongoing.
Research on the Biologic Basis of ASD
Because of its relative inaccessibility, scientists have only recently been able to study the brain systematically. But with the emergence of new brain imaging tools—computerized tomography (CT), positron emission tomography (PET), single photon emission computed tomography (SPECT), and magnetic resonance imaging (MRI), study of the structure and the functioning of the brain can be done. With the aid of modern technology and the new availability of both normal and autism tissue samples to do postmortem studies, researchers will be able to learn much through comparative studies.Postmortem and MRI studies have shown that many major brain structures are implicated in autism. This includes the cerebellum, cerebral cortex, limbic system, corpus callosum, basal ganglia, and brain stem.29 Other research is focusing on the role of neurotransmitters such as serotonin, dopamine, and epinephrine
.
Research into the causes of autism spectrum disorders is being fueled by other recent developments. Evidence points to genetic factors playing a prominent role in the causes for ASD. Twin and family studies have suggested an underlying genetic vulnerability to ASD.30To further research in this field, the Autism Genetic Resource Exchange, a project initiated by the Cure Autism Now Foundation, and aided by an NIMH grant, is recruiting genetic samples from several hundred families. Each family with more than one member diagnosed with ASD is given a 2-hour, in-home screening. With a large number of DNA samples, it is hoped that the most important genes will be found. This will enable scientists to learn what the culprit genes do and how they can go wrong.
Another exciting development is the Autism Tissue Program (http://www.brainbank.org), supported by the Autism Society of America Foundation, the Medical Investigation of Neurodevelopmental Disorders (M.I.N.D.) Institute at the University of California, Davis, and the National Alliance for Autism Research. The program is aided by a grant to the Harvard Brain and Tissue Resource Center (http://www.brainbank.mclean.org), funded by the National Institute of Mental Health (NIMH) and the National Institute of Neurological Disorders and Stroke (NINDS). Studies of the postmortem brain with imaging methods will help us learn why some brains are large, how the limbic system develops, and how the brain changes as it ages. Tissue samples can be stained and will show which neurotransmitters are being made in the cells and how they are transported and released to other cells. By focusing on specific brain regions and neurotransmitters, it will become easier to identify susceptibility genes.
Recent neuroimaging studies have shown that a contributing cause for autism may be abnormal brain development beginning in the infant’s first months. This“growth dysregulation hypothesi” holds that the anatomical abnormalities seen in autism are caused by genetic defects in brain growth factors. It is possible that sudden, rapid head growth in an infant may be an early warning signal that will lead to early diagnosis and effective biological intervention or possible prevention of autism.31
We had some discussion about genetics versus environment. Here is a study that examines that.
http://www.ama-assn.org/amednews/2011/07/18/prse0722.htm
Environmental factors may be more important than previously thought in determining whether a child develops autism, says a study of twins published online in July by theArchives of General Psychiatry.
The findings shake up prior assumptions that genetics were largely the culprit behind the neurodevelopmental disorder, now estimated to affect 1% of the population.
The study, believed to be the largest of its kind, looked at 192 pairs of identical and fraternal twins, in which at least one child in each pair had strict autism or a milder autism spectrum disorder (archpsyc.ama-assn.org/cgi/content/abstract/archgenpsychiatry.2011.76/).
http://www.webmd.com/brain/autism/news/20110608/new-clues-on-genetic-causes-of-autism
June 8, 2011 -- Genetic mutations not inherited from parents appear to explain some cases of autism, new research suggests. And the mutations may number in the hundreds.
While the new research is a step forward, it is a small puzzle piece. "It could explain up to 2% of all autism cases," says researcher Stephan J. Sanders, MD, a postdoctoral research associate at Yale University's Child Study Center.
Even so, he says the new research -- reported as a trio of studies in the journalNeuron -- provides a solid foundation to a better understanding of the biology of the disorder, eventually leading to better treatments.
In the new research, scientists also found new clues about why boys seem to be more vulnerable to the disorder than girls.
''In combination with some other research studies, this new research shows pretty clearly there is indeed a strong genetic component to autism, and that the individual genes can be identified," say Alan Packer, PhD, associate director for research at the Simons Foundation. It funds autism research and provided the sample populations studied in the new research.